1. Field of the Invention
The present invention relates generally to a method for transmitting and receiving channel codes to improve performance of broadcasting and communication systems, and more particularly, to a method and apparatus for mapping generated coded data to modulation symbols, and transmitting and receiving the mapped data.
2. Description of the Related Art
A powerful error-correction coding technique that supports broadband data and high-speed packet transmission is a key element in next-generation mobile communication systems and broadcasting systems. Since the turbo decoding method of 1993, interest in high-performance error-correcting codes showing error probability approaching the Shannon limit has increased, and IMT-2000 systems have employed turbo codes. The core technology of turbo codes is iterative decoding. Iterative decoding has evolved into a new realm of a high-performance decoding method, from which graph-based decoding methods have attracted attention. However, since turbo codes reach their performance limits at a very low error rate, which is required in 4th generation mobile communication systems, the interest in new types of graph-based coding methods has increased. Error-correcting codes that have attracted attention due to this increased interest include a Low Density Parity Check Code (LDPC). The LDPC is a high-performance code that approaches the Shannon limit when a belief-propagation-based iterative decoding algorithm is used.
In situations where a Signal-to-Noise Ratio (SNR) is low or an error occurs frequently, a receiver may not restore input data from received coded data. Instead, a transmitter may transmit additional parity associated with the input data so that the receiver may utilize the parity in restoring the data.
When the additionally transmitted parity is not identical to the first transmitted coded data or any part thereof, the receiver performs decoding taking into account both the first transmitted coded data and the additionally transmitted parity, causing an increase in decoding complexity. In addition, when the additionally transmitted parity is the same as the first transmitted coded data or any part thereof, and data is transmitted in a simple iterative manner using the same modulation symbols, the decoding complexity may be low, but performance improvement may not meet the high standards that are desired.